MEMBRANE PUMP

TECHNICAL FIELD

The present invention relates to the field of pumps, in particular to the field of membrane or diaphragm pumps.

PRIOR ART

Membrane or diaphragm pumps are used especially for pumping water mixed with substances, oils or even liquids containing a high degree of impurities and foreign bodies that would end up wearing out other types of pumps, such as piston pumps.

Membrane pumps generally comprise at least one pumping chamber, which is partly defined by a flexible membrane, e.g. made of rubber or plastic polymer, which is flexed in order to vary the volume of the pumping chamber and thus pump a liquid, thanks also to the presence of automatic suction and delivery valves that are directly connected fluidi- cally to the pumping chamber.

The flexion of the membrane is achieved by means of a membrane drive mechanism which comprises a guide cylinder inside which a piston is slidably accommodated according to a sliding axis perpendicular to a drive shaft of the pump, a shaft, that is which is connected to a motor to supply the pump with the energy required to pump the liquid.

The piston, at one axial end, is fixed to a portion of the membrane and can be connected to a drive shaft by means of a kinematic mechanism that is adapted to transform the rotary movement of the drive shaft into a linear and reciprocating movement of the piston inside the guide cylinder.

In this way, the piston is cyclically adapted to move between a bottom dead centre position, in which it is at the minimum distance from the drive shaft and substantially pulls towards the drive shaft, and a top dead centre position, in which is at the maximum distance from the drive shaft.

The kinematic mechanism comprises an eccentric rigidly fixed to the drive shaft, usually made in a single body therewith, and a connecting rod articulated to said eccentric and to a transversal pin of the piston.

The eccentric can have a substantially cylindrical shape with a central axis that is parallel but spaced with respect to the central axis of the drive shaft. In this manner, a thrust linkage is obtained which is capable of transforming the rotary movement of the drive shaft into a reciprocating movement of the piston. Alternatively, the eccentric may be substantially made as a cam and may directly contact an axial end of the piston opposite to that integral with the membrane and which is maintained in contact with said cam by means of an elastic element configured to exert a force in a direction of approach of the piston to the cam.

A problem with the proposed solutions is that the use of the eccentric limits the maximum rotation speed, due to the vibrations that are caused by its unbalanced mass with respect to the axis of rotation.

An object of the present invention is to overcome the constraints of the prior art within the scope of a rational and low-cost solution which makes available a membrane pump capable of operating at higher rotation speeds than those of known devices and which can therefore process a higher flow rate than known devices with the same size of the pump. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

DISCLOSURE OF THE INVENTION

In particular, the invention makes available a membrane pump comprising a pumping chamber, partially defined by a flexible (resilient elastic) membrane, and a membrane drive mechanism configured to flex the membrane in order to vary a volume of the pumping chamber, said drive mechanism comprising a swash plate rotatable with respect to an axis of rotation and configured to push the flexible membrane so as to flex it.

Thanks to this solution, a membrane pump is made available which is capable of operating at higher rotation speeds than those typical of membrane pumps of the prior art, which use an eccentric to drive the flexion of the membrane, as the swash plate has a more homogeneous mass distribution around the axis of rotation than the eccentric and consequently generates vibrations of lower intensity with the same speed of rotation. Thanks to the greater propensity to operate at a higher number of revolutions, the pump according to the invention allows a higher flow rate to be obtained with the same volume of the pumping chamber, thus with the same size of the pump.

According to one aspect of the invention, the drive mechanism may comprise:

- a piston, and

- a guide cylinder of the piston, to which the piston is slidingly associated with respect to a sliding axis, wherein the swash plate is configured to push the piston (cyclically during rotation) along the sliding axis, in contrast to an elastic element which acts on the piston along the sliding axis, during its rotation about the axis of rotation.

This makes the drive particularly robust, efficient and long-lasting.

According to another aspect of the invention, the pump may comprise at least three pumping chambers (arranged radially with respect to the axis of rotation), each of which is provided with a suction mouth and a delivery mouth. All the suction mouths are in fluid connection with each other by means of suction ducts, which are in fluid communication with an inlet mouth, and all the delivery mouths are in fluid connection with each other by means of delivery ducts, which are in fluid communication with an outlet mouth. In addition, a section of said suction ducts and of said delivery ducts is made in the same monolithic body.

This makes the pump particularly compact and quick to assemble.

According to yet another aspect of the invention, at least one section of a delivery duct is superimposed on a section of a suction duct along a direction parallel to the axis of rotation.

In the case of two-membrane pumps, it is easy to create a compact suction duct and delivery duct system, as the suction mouths and the delivery mouths of the pumping chambers can be connected directly with rectilinear ducts, however, as the number of pumping chambers increases, it is difficult to create a compact duct system. Compactness is particularly important in the delivery ducts, as it is important to minimise the surface affected by pressure pulsations. The above characteristics allow these compactness advantages to be achieved.

An alternative characteristic that allows to achieve this advantage is the following, in which the pump may comprise at least three pumping chambers, each of which is provided with a suction mouth and a delivery mouth, wherein all the suction mouths are in fluid connection with each other by means of a suction duct, wherein all the delivery mouths are in fluid connection with each other by means of a delivery duct, and wherein the suction mouths are all placed at a radial distance from the axis of rotation which is less than the radial distance of any one of the delivery mouths.

The invention may also provide that the sliding axis of the piston may be inclined between 5° and 30° with respect to the axis of rotation of the swash plate.

This makes it possible to use larger membranes, thus more voluminous pumping chambers, or to increase the number of pumping chambers, without having to increase the size of the plate, which allows to reduce costs, standardise production and reduce vibrations since the mass distribution of the swash plate is not homogeneous (although in any case it is more homogeneous than the eccentrics of prior art).

The invention may further provide that the pump may comprise a system for blocking the relative rotation between the guide cylinder and the piston.

The rotation of the swash plate can cause the piston to rotate due to its rubbing against the surface of the swash plate. Such a rotation would cause an unwanted torsion of the membrane and consequently the possibility of premature wear and/or malfunction. Thanks to the proposed solution, the piston is prevented from being able to rotate and consequently unwanted torsions of the membrane are avoided.

According to an aspect of the invention, the system for blocking the relative rotation between the guide cylinder and the piston may comprise a pin integral with the guide cylinder, parallel to the sliding axis and at least partially inserted in a hole made in a portion of the piston and shaped to accommodate said pin to size.

In this way, a simple blocking system is made available, which is therefore robust given the few elements required and their simplicity, and which is quick and economical to produce.

The invention may further provide that the drive mechanism may comprise a drive shaft of the pump rotatable with respect to an axis of rotation and on which a first toothed wheel coaxial to the axis of rotation is mounted, and wherein the swash plate is rotatable with respect to an axis of rotation eccentric with respect to said axis of rotation and is rotation- ally integral with respect to said axis of rotation together with a second toothed wheel which meshes with the first toothed wheel.

In this way, the swash plate can be particularly compact from the point of view of its diameter, thus allowing, other construction factors being equal, to rotate at higher speeds without generating dangerous vibrations, and consequently to increase the flow rate of the pump. In addition, this makes it possible to create pumps with a high flow rate, thus large and/or numerous pumping chambers, with reduced vibrations. For example, in the case of a large number of pumping chambers, there may be a small swash plate for each pumping chamber, connected to the drive shaft in the manner described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will be more apparent after reading the following description provided by way of non-limiting example, with the aid of the accompanying drawings.

Figure 1 is an axonometric view of a pump according to the invention.

Figure 2 is a front view of the pump of Figure 1 .

Figure 3 is a sectional view of the pump of the previous figures according to the section plane Ill-Ill.

Figure 4 is an enlargement of the detail IV of Figure 3.

Figure 5 is a sectional view of the pump of Figure 2, sectioned according to the section profile V-V.

Figure 6 is a side view of the pump of the previous figures.

Figure 7 is a sectional view of the pump of Figure 6 according to the section plane VII-

VII.

Figure 8 is a sectional view of the pump of Figure 6 according to the section plane VIII-

VIII.

Figure 9 is a sectional view of the pump of Figure 6 according to the section plane IX-IX. Figure 10 is a partial and schematic sectional view of another embodiment of the pump according to the invention, in which some hidden elements with dashed lines are shown. Figure 1 1 is a front view of yet another embodiment of the pump according to the invention.

Figure 12 is a front view of the pump of Figure 1 1 , in which a suction duct has been removed in order to make some components underneath visible.

Figure 13 is a sectional view of the pump of Figure 1 1 according to the section plane XIII- XIII.

Figure 14 is an enlargement of the detail XIV of Figure 13.

Figure 15 is a sectional view of a further embodiment of the pump according to the invention, sectioned according to a section plane containing the axis of rotation of a drive shaft of the pump.

Figure 16 is a sectional view of yet another embodiment of the pump according to the invention, further with respect to all the previous embodiments, sectioned according to a section plane containing the axis of rotation of a drive shaft of the pump.

Figure 17 is a sectional view of yet another embodiment of the pump according to the invention, which substantially constitutes a variant of the embodiment of Figure 16. In Figure 17, the pump is sectioned according to a section plane containing the axis of rotation of a drive shaft of the pump.

BEST MODE TO IMPLEMENT THE INVENTION

With particular reference to these drawings, different embodiments of a volumetric membrane pump for pumping fluids, in particular for pumping liquids have been indicated with 1 a,1 b,1 c,1 d,1 e,1 f. For example, the pump 1 a,1 b,1 c,1 d,1 e,1 f may be used in the agricultural field for pumping protective liquids, fertilizing liquids or liquids of other type towards specific dispensing nozzles intended to spray or in any case dispense such liquids over the crops. However, it is not excluded for the pump to also be used in other fields and/or for pumping other types of fluids.

The pump 1 a,1 b,1 c,1d,1 e,1 f comprises a drive shaft 5,5’, which is adapted to rotate on itself about its own central axis X, which therefore represents an axis of rotation X of the same drive shaft.

The rotation of the drive shaft 5 may be obtained by direct or indirect connection with an internal combustion engine, for example with the engine of an agricultural tractor through a power take-off, or with an electric motor.

In detail, the pump 1 a,1 b,1 c,1 d,1 e,1 f comprises a baseplate with respect to which the drive shaft 5 is rotatably associated according to the axis of rotation X, for example by interposition of bearings or bushings. Preferably, the drive shaft 5 is also partially contained in the baseplate and protrudes externally through an opening made in the baseplate. In particular, this portion of the drive shaft which protrudes externally comprises a splined tang for transmitting the rotary motion.

In said opening there is an annular sealing gasket which sealingly embraces a portion of the drive shaft, preventing foreign bodies from entering the baseplate through the opening.

The drive shaft could also pass through the entire body of the pump so as to protrude from both sides, as illustrated in the embodiment of the pump of Figure 16. In this case, the drive shaft 5’ comprises two opposite splined tangs for the connection to a drive motor of the pump which protrude either from two openings made in the baseplate or from said opening made in the baseplate and an opposite opening made in a head integral with the baseplate.

This configuration of the drive shaft, although illustrated only in Figure 16, is applicable to all other embodiments of the pump with appropriate modifications to the other components, as is known to the person skilled in the art.

The baseplate can comprise a fixing flange adapted to allow the pump to be fixed to an external body, such as for example the motor adapted to rotate the drive shaft 5.

In the embodiment illustrated, the baseplate comprises (for example only) a first portion 10 and a second portion 15 which is made as a separate body from the first portion and fixed to the first portion without residual degrees of freedom, preferably in a removable way (for example by means of threaded connection members).

The first portion 10 is the one in which the opening crossed by the drive shaft 5 is made and in which there is a housing seat for at least one bearing through which the drive shaft 5 is rotatably associated with the baseplate.

The second portion has a tubular body which defines an external side wall of the pump and which is provided with an opening (with a larger diameter than the opening from which the drive shaft comes out) at least partially closed by the first portion.

In particular, the first portion extends in the radial direction away from the opening (direction away from the axis of rotation X) up to a perimeter edge at which it is removably fixed to the second portion, i.e. the side wall defined by it.

In other words, the first portion is made as a discoidal or glass- or cup-shaped body, in the centre of which the opening is made and whose outermost perimeter edge is in contact with the second portion and fixed thereto, so as to close one end of the tubular body of the second portion. The perimeter edge therefore has a diameter substantially equal to the diameter of the opening.

The fixing flange may be fixed to either the first portion or to the second portion of the baseplate, or be an integral part of either of the two.

The second portion, like the first one, may house a seat for housing a bearing that rotationally supports the drive shaft 5, in addition to or as an alternative to the bearing housed in the first portion.

The baseplate, i.e. the first and the second portion of the baseplate are preferably made of polymeric material. The pump comprises a pumping chamber 20 partially defined by a flexible membrane 25 (elastic, i.e. resilient, e.g. made of rubber), the flexion of which causes a change of a volume (of the entire internal volume) of the pumping chamber.

With particular reference to the enlargement of Figure 4, the flexible membrane 25 has a first major face 30, for example turned towards the inside of the pumping chamber, and a second major face 30 opposite the first major face, for example turned towards an internal volume of the baseplate.

The membrane also has a perimeter edge 40 which protrudes in the direction away from both the first major face and the second major face. Basically, the perimeter edge is therefore a raised edge with respect to both faces.

The perimeter edge 40 is preferably accommodated, at least partially, in a housing seat made in the baseplate, particularly in the second portion of the baseplate.

Such a flexible membrane 25 is preferably made as a discoidal (circular) body with nonzero thickness and continuous without interruption. For example, for reasons that will be clear below, the flexible membrane is a body with non-zero thickness without interruptions except for a single through hole made in a central portion of the membrane. This hole, in particular, extends from the first major face to the second major face, penetrating through them.

In the embodiment illustrated, there are preferably a plurality of (identical) pumping chambers 20, preferably in a number equal to or greater than three, each provided with a respective flexible membrane 25.

In the embodiments of the pump of Figures 1 -9 and 1 1 -15 there are three pumping chambers, in the embodiments of Figures 10 and 16 there are five pumping chambers.

Irrespective of the number of pumping chambers 20, they are arranged radially around the axis of rotation X. Furthermore, they are placed at the same distance from each other and at the same distance from the axis of rotation X. Furthermore, the pumping chambers 20 are angularly arranged equidistant from each other along an imaginary circumference centred on the axis of rotation X and lying on a plane perpendicular to the axis of rotation X.

The pumping chambers 20 are all fixed in space with respect to the baseplate.

All the flexible membranes 25 are arranged with the second major face 35 turned in a single direction, in particular towards the baseplate. The pump 1 a,1 b,1 c,1 d,1 e,1 f then comprises a drive mechanism of the flexible membrane 25, that is for driving the flexible membranes 25, configured to flex the membrane (cyclically based on the rotation of the drive shaft) in order to vary the volume of the pumping chamber 20. In practice, the membrane drive mechanism is configured to flex each membrane (cyclically based on the rotation of the drive shaft) in order to vary the volume of each pumping chamber.

In all embodiments of the pump, the drive mechanism comprises a swash plate 45 rotatable with respect to an axis of rotation (corresponding to a central axis of the plate) and configured to push the flexible membrane so as to flex it (cyclically during the rotation with respect to its axis of rotation), thereby varying the volume of the pumping chamber.

In particular, the swash plate 45 is provided with an inclined annular surface 50, which is inclined with respect to said axis of rotation of the swash plate 45, is coaxial to the axis of rotation of the swash plate 45 and is configured to push (cyclically during said rotation) the flexible membrane so as to flex it. The inclined annular surface 50 lies on a plane that is inclined with respect to the axis of rotation of the swash plate 45. For example, this plane forms an acute angle with the axis of rotation of the swash plate 45 comprised between 5° and 20°. Further, this annular surface is turned towards the flexible membrane 25, i.e. towards the second major face of the membrane.

The swash plate 45 is entirely accommodated within the pump, for example within the baseplate, in particular at the first portion 10 of the baseplate.

In all the embodiments of the pump, the swash plate 45 comprises a discoidal body, for example provided with a through hole into which it is inserted, so as to achieve a rotationally integral coupling (by shrink fitting or key or otherwise), with a portion of a shaft by means of which the swash plate 45 is rotatably associated with the rest of the pump, for example with a portion of the drive shaft. However, it is not ruled out that the shaft and the discoidal body could be made as a single piece. In this case the through hole is not present.

Said discoidal body comprises a first major face which makes available the inclined annular surface 50 and which is turned towards the pumping chamber, i.e. the pumping chambers, an opposite second major face (substantially perpendicular to the axis of rotation of the swash plate 45) and a cylindrical lateral surface which connects, along an external peripheral edge of the discoidal body, the first major face and the second major face.

The plate is therefore substantially a discoidal body having a thickness (intended as the distance between the major face and the minor face) which varies based on the distance from the axis of rotation and is symmetrical with respect to a plane containing the axis of rotation of the plate.

The swash plate 45 is rotated by the drive shaft 5 (also forming part of the drive mechanism) which is mechanically connected to said swash plate 45 in such a way as to rotate it with respect to the axis of rotation of the swash plate 45.

In the embodiments of the pump 1 a,1 b,1 c,1 d illustrated from Figure 1 to Figure 15, the axis of rotation of the plate corresponds to the axis of rotation X.

In such a case, the swash plate 45 is coaxial to the drive shaft (and to the axis of rotation X) and is (directly) rotationally integral therewith with respect to the axis of rotation X. For example, the plate may be keyed onto the drive shaft 5 or connected thereto by means of a key or a splined coupling.

In these embodiments, the inclined annular surface 50 is therefore inclined with respect to the axis of rotation X, i.e. it lies on a plane inclined with respect to the axis of rotation X.

In the embodiment of the pump 1 e illustrated in Figure 16, the swash plate 45 is instead rotatable with respect to an axis of rotation X’ which is eccentric (and parallel) with respect to the axis of rotation X.

In such a case, the swash plate 45 is thus hinged to the baseplate, in particular to the first portion of the baseplate, for example connected to the baseplate by means of a respective eccentric shaft to the drive shaft 5 and rotatably coupled to the baseplate by interposition of at least one respective bearing.

In this embodiment, the drive mechanism comprises a transmission group between the drive shaft and the swash plate 45 of the rotary motion around the respective axes of rotation X and X’ (a shaft integral with the swash plate 45).

For reasons of compactness and robustness, a preferred embodiment comprises a first toothed wheel 55 coaxial to the axis of rotation X and integral with the drive shaft 5 in rotation about the axis of rotation X, which first toothed wheel 55 meshes (directly) with a second toothed wheel 60 coaxial to the axis of rotation X’ and rotationally integral with respect to said axis of rotation X’ with the swash plate 45. This embodiment, in which the axis of rotation of the swash plate is eccentric with respect to the axis of rotation of the drive shaft, preferably further provides that, in the case of a plurality of pumping chambers, there is a plurality of swash plates, one for each pumping chamber, all (directly) mechanically connected to the drive shaft 5 to be rotated by it with respect to respective axes of rotation X’,X” that are eccentric (and parallel) to the axis of rotation X.

These swash plates are arranged radially around the axis of rotation X. Furthermore, they are placed at the same distance from each other and at the same distance from the axis of rotation X. Furthermore, the swash plates are angularly arranged equidistant from each other along an imaginary circumference centred on the axis of rotation X and lying on a plane perpendicular to the common axis.

Thus, in such an embodiment, the drive mechanism comprises a plurality of second toothed wheels 60, each rotationally integral with a respective swash plate 45 and all of them meshing (directly) with the first toothed wheel 55 that is rotationally integral with the drive shaft.

It is not excluded that in embodiments not illustrated the transmission of the motion may take place by means of belts and pulleys or other mechanisms for transmitting the rotary motion.

The swash plate 45, i.e. the discoidal body, is preferably made of polymeric material.

In all the illustrated embodiments of the pump, the drive mechanism of the flexible membrane preferably comprises a piston 65 that is fixed (without residual degrees of freedom) to a portion of the flexible membrane 25, for example the central portion of the flexible membrane, preferably by means of a threaded connection member inserted in the hole of the flexible membrane 25.

For example, the piston 65 comprises a first axial end 70 that is fixed (without residual degrees of freedom) to the portion of the flexible membrane 25, and an opposite second axial end 75 that is turned towards the swash plate 45, i.e. the inclined annular surface 50.

In particular, the inclined annular surface 50 pushes on the second axial end 75, for example indirectly by interposition of a flat annular guide disc 80, which is free to slide with respect to the inclined annular surface 50 by interposition between itself and said inclined annular surface of a rolling bearing, for example a needle bearing. This flat annular guide disc 80 is provided with two opposite major faces that are flat and parallel to each other and parallel to the inclined annular surface.

As mentioned above, the piston 65 is fixed at the first axial end 70 to the flexible membrane 25 and this is achieved by means of a screw 85 which is inserted into the through hole of the flexible membrane and which is screwed into a threaded hole made in the first axial end 70. A portion of the flexible membrane is thus clamped between a head of the screw, for example between a washer 90 placed between the head of the screw and the flexible membrane, and the first axial end 70.

The piston 65 is substantially solid, in particular there are no channels for the passage of fluid between the piston 65, i.e. the inside of the piston 65, and the pumping chamber.

Said piston 65 is slidably accommodated, with reduced clearance, along a sliding axis Z in a guide cylinder 95 which defines this sliding axis and which is at least partially interposed between the swash plate 45, i.e. its first major face, and the flexible membrane 25. The guide cylinder 95 is at least partially made available by the baseplate, in particular by the second portion 15 of the baseplate.

The sliding axis Z defined by the guide cylinder 95 intersects the inclined annular surface 50.

In the embodiments of the pump 1 a,1 b,1 c,1 e, the sliding axis Z is substantially parallel, preferably exactly parallel (net of the geometrical constructional tolerances), to the axis of rotation of the swash plate 45, i.e. to the axis of rotation X. Parallel substantially means that the sliding axis Z forms an acute angle of less than 2° with the axis of rotation of the plate.

In the embodiment of the pump 1d illustrated in Figure 15, the sliding axis Z is instead inclined with respect to the axis of rotation of the plate, i.e. with respect to the axis of rotation X (and is also inclined with respect to an axis perpendicular to the axis of rotation X).

In this way the pumping chamber, i.e. the pumping chambers, can have larger dimensions, in particular the flexible membranes can have larger dimensions (to be understood as the dimensions of the major faces) for the same dimensions of the swash plate 45. Alternatively or additionally, this inclined configuration of the sliding axis makes it possible to create a pump with a greater number of pumping chambers, while maintaining a swash plate 45 with limited dimensions. In particular, in this embodiment, the sliding axis Z forms an acute angle greater than 5° with the axis of rotation of the plate, preferably greater than 10°, for example comprised between 10° and 25°. In the embodiment illustrated, the sliding axis Z forms an acute angle of 13° with the axis of rotation of the swash plate 45, i.e. with the axis of rotation X. The second axial end of the piston 65 (always) protrudes at least partially from a portion of the guide cylinder 95 proximal to the swash plate 45, so as to contact the swash plate 45, that is the inclined annular surface 50, or, like in the embodiments illustrated, the flat annular guide disc 80.

In particular, the pump comprises an elastic element 100, for example in the form of a helical compression spring, which pushes the piston 65, i.e. the second axial end 75 thereof, while keeping the second axial end 75 in contact with the swash plate 45, i.e. the inclined annular surface 50, or, like in the embodiments illustrated, the flat annular guide disc 80.

The swash plate 45 thus pushes the piston 65 (the second axial end 70) along the sliding axis Z (cyclically during the rotation about its own axis of rotation) in contrast to the force exerted by the elastic element.

In particular, the elastic element 100 is interposed between the guide cylinder and the second axial end 75, so as to push the second axial end in a direction away from the portion of the guide cylinder proximal to the swash plate 45.

Even more in detail, the elastic element 100 comprises a first longitudinal end which is placed in contact with a first abutment surface formed in the guide cylinder (or in the body that makes the guide cylinder available) and which is turned towards the swash plate 45. Furthermore, the elastic element 100 comprises a second longitudinal end which is placed in contact with a second abutment surface made in the second longitudinal end of the piston 65 and which is turned towards the guide cylinder. For example, this second abutment surface is made available by a ring inserted in an annular cavity made in the second longitudinal end 75 and which protrudes radially with respect to a casing of the piston 65.

Thanks to the elastic element 100 and to the swash plate 45, the piston 65 is cyclically movable, during the rotation of the swash plate 45 around its axis of rotation, between a top dead centre, in which the volume of the pumping chamber is minimum, and a top dead centre, in which the volume of the pumping chamber is minimum. The guide cylinder also comprises at least one through hole adapted to place a volume internal to the guide cylinder and included between the flexible membrane and the first axial end 70 in fluid communication with an internal volume of the baseplate inside which the swash plate 45 is placed.

In the illustrated embodiments of the pump, the piston 65 is of the differential type and at the first axial end has a larger diameter than the second axial end. In detail, the piston 65 has a first cylindrical body which makes available the first axial end 70 and which is provided with a first major face turned towards the membrane and a second major face turned in the opposite direction and a portion from which a second cylindrical body develops, with a diameter smaller than the first cylindrical body and coaxial thereto, which makes available the second axial end 75.

The guide cylinder is shaped to guide both the first axial end and the second axial end and thus comprises two tubular bodies each provided with a cylindrical internal surface for guiding the respective end of the piston 65. In particular, with reference to the enlargement of Figure 14, the guide cylinder comprises a first tubular body has a cylindrical internal surface 105 dimensioned so as to accommodate the first axial end to size, and a second tubular body coaxial to the first one has a cylindrical internal surface 1 10 dimensioned so as to accommodate the second axial end to size. The enlargement of the embodiment 1 c which illustrates in detail the first and the second tubular body is taken only as a reference and what is represented therein applies to all the embodiments of the pump.

The two tubular bodies may be separated from each other by an annular interspace or a plurality of holes, both of which are adapted to place an internal volume of the guide cylinder, placed between the second major face of the first cylindrical body and the second longitudinal end, in fluid communication with the rest of the volume of the baseplate. In the embodiments illustrated, the second tubular body is always made available by the baseplate, i.e. by the second portion of the baseplate.

The first tubular body may be a body separated from the second portion of the baseplate and inserted in an accommodating seat made in the second portion of the baseplate, or, like in Figure 16, it may be made in a body integral with the second portion of the baseplate.

The piston 65 and the guide cylinder are preferably made of polymeric material. The above description of the drive mechanism is present for each flexible membrane 25, hence for each pumping chamber 20 of the pump. In particular, there is a piston 65, a guide cylinder, and an elastic element 100 for each flexible membrane.

The pump, in all embodiments, comprises a system for blocking relative rotation between the guide cylinder and the piston 65, i.e. which prevents a rotation of the piston 65 with respect to the guide cylinder about the sliding axis Z.

The blocking system comprises a rigid element integral with the baseplate and with which the piston 65 is slidingly associated along an axis parallel to the sliding axis Z.

For example, with particular reference to the enlargements of Figure 4 and Figure 4, the system for blocking the relative rotation between the guide cylinder and the piston 65 comprises a (rigid) pin 120, for example cylindrical, integral with the guide cylinder 95 (or with the baseplate, that is with the second portion of the baseplate), (arranged with a respective longitudinal axis) parallel to the sliding axis Z and at least partially inserted (with clearance, for example reduced) into a housing seat 125 (for example a blind hole) made in a portion of the piston 65 and arranged with a longitudinal axis parallel to the sliding axis Z.

In particular, the pin 120 comprises a first portion inserted into a seat 130 made in a portion of the guide cylinder (or in the baseplate) and to which it is fixed without residual degrees of freedom, for example by being inserted into the seat by elastic or plastic deformation.

The pin 120 then comprises a second portion which protrudes with respect to the guide cylinder 95 in a direction parallel to the sliding axis Z and which is inserted into the seat 125 made in the piston 65. The seat 125 is complementary in shape to the protruding portion of the pin, for example therefore cylindrical, and accommodates this portion with reduced clearance, so that the piston 65 can slide with respect to the pin, but cannot rotate about the sliding axis Z.

In detail, the seat 125 made in the first cylindrical body of the piston is shaped like a cylindrical blind hole parallel to the sliding axis Z and provided with an opening made in the second major face of the first cylindrical body and which is crossed by the second portion of the pin (protruding portion).

It is not excluded that in alternative, not illustrated and less preferred embodiments, the system for blocking the relative rotation between the piston 65 and the guide cylinder may be obtained by a prismatic coupling between the piston 65 and the guide cylinder.

The system for blocking the relative rotation between the guide cylinder and piston 65 is also present for each piston 65, and therefore for each flexible membrane.

All pistons are slidable independently of each other with respect to the respective guide cylinders (with the obvious exception of the law of motion imparted by the swash plate 45 to the pistons).

It is not excluded that in an alternative, not illustrated and less preferred embodiment, the drive mechanism may not comprise the piston 65 and the relative guide cylinder and the elastic element 100. In such a case, the swash plate 45 could push directly on the membrane, or possibly on a pin integral with the membrane in order to avoid wear problems due to sliding. This pin would be bound only to the membrane and would not slide in any guide. Yet another embodiment which does not provide for the presence of pistons comprises a pin provided with a longitudinal end integral with the membrane and an opposite longitudinal end shaped to fit into an annular guide made in the swash plate 45 so that the swash plate 45 and the pin substantially form a cylindrical cam mechanism.

In particular, the annular guide retains this end of the pin in a direction parallel to the axis of rotation X so that this end moves according to the inclined profile of the plate towards and away from a central portion of the pumping chamber, while at the same time allowing it to slide with respect to the rotation about the axis of rotation X, i.e. to remain stationary together with the membrane with respect to this axis of rotation. In detail, this end comprises at least one narrow section which fits into a groove in the guide which is shaped so as to retain the axial end of the pin in the direction of the axis of rotation X, while allowing it to slide with respect thereto so that during the rotation of the plate the pin moves closer and away.

The pump is of the type provided with automatic suction and delivery valves for regulating the pumping flow. That is, the pumping chamber, or rather each pumping chamber, is in direct fluid communication with one (only) suction valve 140 (of automatic type) and one (only) delivery valve 145 (of automatic type).

It should be noted that an automatic valve is understood to be a one-way valve which is driven by a pressure difference between an environment upstream and an environment downstream thereof with respect to the direction of the flow of the liquid.

For example, in the embodiment illustrated, each suction 140 or delivery valve comprises a shutter which is pushed (only) by an elastic element 100 in contact with a housing seat so as to form a hermetic seal.

Each pumping chamber comprises a suction mouth 150 in fluid communication with a suction valve 140, for example by means of a suction channel 160, and a delivery mouth 155 in fluid communication with the delivery valve 145, for example by means of a delivery channel 165 (see in particular the enlargements of Figures 5 and 14).

The pump comprises a cap 170 (or head) which together with the flexible membrane 25 partially defines the volume of the pumping chamber 20, for example it defines most of the volume of the pumping chamber. In particular, there is a single cap 170 (or head) for each pumping chamber 20.

In contrast to the flexible 25 membrane, the cap 170 is rigid.

It should be noted that the term rigid in this discussion means not elastically or plastically deformable to a significant degree under the normal working loads to which the rigid element is subjected.

Each cap 170 is fixed to the baseplate, in particular to the second portion 15 of the baseplate, for example removably, preferably removably by means of a plurality of threaded connection members which can be screwed in the baseplate.

In addition, the cap 170 is fixed to the baseplate so as to clamp the perimeter edge 40 of the respective flexible membrane between itself and the baseplate. In the illustrated embodiments of the pump, the cap 170 comprises an annular groove for accommodating a portion of the perimeter edge of the flexible membrane.

Further, in the embodiments illustrated, said perimeter edge of the flexible membrane is pressed directly into contact between the cap 170 and the first tubular body of the guide cylinder, which also has an annular groove for accommodating a portion of the perimeter edge of the flexible membrane.

However, it cannot be ruled out that in an embodiment not illustrated, instead of the plurality of caps 170 made in separate bodies and fixed independently to the baseplate, there may be a single head in which cavities are made which at least partially make up the pumping chamber together with the flexible membrane.

Each cap 170 makes available the suction mouth and the delivery mouth, which are for example made in an internal surface of the cap 170 facing onto the pumping chamber. This internal surface of the cap 170 is for example concave with a concavity turned towards the inside of the pumping chamber.

The cap 170 further makes available the suction channel 160 and the delivery channel 165, which develop (as tubular bodies) from the respective suction 150 and delivery 155 mouths in a direction away from the flexible membrane 25, preferably along a direction substantially parallel to the axis of rotation X or to the sliding axis Z.

In the embodiments illustrated, the cap 170 is therefore substantially shaped as a concave shell (with a single concavity) of reduced thickness, from which the tubular bodies develop which make the suction and delivery channels available, by protruding from an external surface of said cap 170 opposite to the internal surface turned towards the pumping chamber (the distance between the internal surface and the external surface defines the thickness of the cap).

Each cap 170 is preferably made of polymeric material.

The suction mouths 150, i.e. the suction channels 160, of each pumping chamber 20 are in fluid communication, by means of the respective suction valves 140, with a suction channelling, which for example originates from an inlet mouth 180 adapted to be connected to a source of liquid to be pumped and which feeds the fluid to the various pumping chambers.

The suction channelling comprises a plurality of suction ducts, one for each suction valve 140 and e.g. each placing the respective suction valve 140 (or the respective suction mouth 150) in fluid connection with the inlet mouth 180.

In the embodiment illustrated, the suction ducts substantially develop starting from a (longitudinal) end of the respective suction channel 160 distal from the pumping chamber.

In the embodiment illustrated, each suction valve 140 is positioned within the respective suction duct, in particular in a portion of said suction duct proximal to the respective pumping chamber, or it is positioned in the respective suction channel. However, it is not excluded that equivalently the suction valve can also be positioned partially or totally inside the respective suction channel.

Similarly, the delivery mouths 155, i.e. the delivery channels 165, of each pumping chamber 20 are in fluid communication, by means of the respective delivery valves 145, with a delivery channelling, which for example originates from an outlet mouth 185 from which all the fluid pumped in the different pumping chambers 20 exits. The delivery channelling comprises a plurality of delivery ducts, one for each delivery valve 145 and for example each placing the respective delivery valve 145 (or the respective suction mouth 155) in fluid connection with the outlet mouth 185.

In the embodiment illustrated, the delivery ducts substantially develop starting from a (longitudinal) end of the respective delivery channel 165 distal from the pumping chamber.

Each delivery valve 145 is positioned within the respective delivery duct, in particular in a portion of said delivery duct proximal to the respective pumping chamber, or it is positioned in the respective delivery channel. However, it is not excluded that equivalently the delivery valve can also be positioned partially or totally inside the respective delivery channel.

In order to realise compact suction and delivery channellings, in the event that there are at least three pumping chambers, the present invention makes available various embodiments of such channellings.

Figures 1 -9 show a first embodiment of these suction channellings, referred to as pump 1 a.

This embodiment is characterized in that at least one section of each suction duct, for example a section of all the suction ducts, and a section of each delivery duct, for example a section of all the delivery ducts, is made within the same (central) monolithic body 190. In the embodiment illustrated, also the inlet mouth 180 and the outlet mouth 185 are made in the monolithic body 190.

The monolithic body is preferably made of polymeric material.

The monolithic body comprises a first major face turned towards the caps and the baseplate (and facing onto them), and an opposite second major face turned in the opposite direction.

The monolithic body also comprises a perimeter edge that joins the first major face to the second major face and is radially arranged about the axis of rotation X.

The monolithic body is aligned to the baseplate according to a direction parallel to the axis of rotation X, for example the monolithic body is centred on the axis of rotation X. The monolithic body is further aligned along this direction to a portion of each cap 170 proximal to the axis of rotation X.

It should be noted that a monolithic body is understood to be a body obtained by cooling and possible subsequent mechanical processing of a single casting or injection of material into a mould.

The aforesaid sections of duct are to be understood as portions of duct comprising an internal annular surface in direct contact with the liquid and which is continuous without interruption radially with respect to the direction of the liquid in the section. In other words, or additionally, the section is a portion comprised between two planes transversal (perpendicular) to the direction of the liquid in the section and spaced by a non-zero amount from each other.

Said sections each represent at least 40% of the longitudinal extension of the respective suction or delivery duct, preferably at least 60%.

At least one section of a delivery duct made in the monolithic body 190 may be superimposed on a section of a suction duct also made in said monolithic body 190 along a direction parallel to the axis of rotation X.

In particular, at least said section of a delivery duct of the plurality of delivery ducts and said section of a suction duct of the plurality of suction ducts are aligned with each other along a direction parallel to the axis of rotation X. In detail, in this alignment portion of the monolithic body 190, the delivery duct and the suction duct are fluidically separated by a single same wall 205 (of non-zero thickness) transversal to the axis of rotation X (see Figures 3 and 5).

Furthermore, all the sections of the suction ducts made in the monolithic body 190 develop from a peripheral portion, for example from the peripheral edge, of the monolithic body 190 in a direction towards the axis of rotation X, for example said direction being rectilinear from a viewpoint in which the axis of rotation is a point in a plane.

Said sections intersect each other so that they are all in fluid communication with each other (upstream of the suction valves for the suction ducts and downstream of the delivery valves for the delivery ducts) and at least one of said sections is in direct fluid communication with an inlet duct 195 terminating in the inlet mouth 180.

It can be envisaged, like in the embodiment illustrated in Figures 1 -9, that the ducts develop towards the axis of rotation X up to the same intersection volume (or chamber), also made in the monolithic body 190, in which all the suction ducts converge into one another and from which the inlet duct 195 develops.

The intersection volume of the suction ducts is radially closer to the axis of rotation X than the suction valves and the delivery valves.

Furthermore, all the sections of the delivery ducts made in the monolithic body 190 develop from a peripheral portion, for example from the peripheral edge, of the monolithic body 190 in a direction towards the axis of rotation X, for example said direction being rectilinear from a viewpoint in which the axis of rotation is a point in a plane.

Said sections of the delivery ducts intersect each other so that they are all in fluid communication with each other (upstream of the suction valves and downstream of the delivery valves) and at least one of said sections is in direct fluid communication with an outlet duct 200 terminating in the outlet mouth 185.

In the embodiment illustrated in Figures 1 -9, all the sections develop up to the same intersection volume (or chamber), also made in the monolithic body 190, in which the delivery ducts converge into one another and from which the outlet duct 200 develops, terminating in the outlet mouth.

The intersection volume of the suction ducts is radially closer to the axis of rotation X than the suction valves and the delivery valves.

In this embodiment, the suction mouth 150 and the delivery mouth 155 of each pumping chamber 20 are at least partially made, preferably entirely made, in one half of the respective pumping chamber, that is of the respective cap 170, distal from the axis of rotation X. Furthermore, the suction channel 160 and the delivery channel 165 of each pumping chamber 20 are at least partially made, preferably entirely made, in one half of the respective pumping chamber, that is of the respective cap 170, distal from the axis of rotation X,

For example, the suction channel and the delivery channel of each pumping chamber are placed at the same distance from the axis of rotation X.

The suction channel and the delivery channel of each pumping chamber are further aligned with each other according to a respective direction lying on a plane perpendicular to a plane on which the axis of rotation X lies. Altogether each pair of suction and delivery channels of each pumping chamber are aligned along these directions, and said planes on which the axis of rotation X of each pair lies are angularly equidistant from each other. Furthermore, these channels are arranged with longitudinal axis substantially parallel to the axis of rotation X.

Returning to the monolithic body 190, it is directly fixed to the baseplate by means of a single threaded connection member coaxial to the axis of rotation X and inserted in a through hole of the monolithic body 190 (extending from the first major face to the second major face) coaxial to the axis of rotation X and made in the monolithic body 190.

In particular, the baseplate, that is the second portion, comprises a threaded hole coaxial to the axis of rotation X, in which a screw 210, inserted into the through hole of the monolithic body 190, is screwed and provided with a head having a diameter greater than the shank, such as to clamp a portion of the monolithic body 190 between itself and the baseplate.

The sections of the suction and delivery ducts made in the monolithic body 190 therefore do not intersect the axis of rotation X (nor the through hole for inserting the threaded connection member). The intersection volumes are therefore made in a portion of the monolithic body 190 comprised between the through hole and the delivery and suction valves, without intersecting the through hole.

Obviously, this conformation is possible when the drive shaft does not pass through the pump.

The pump 1 a,1 b, i.e., an assembly consisting of the suction channelling and the delivery channelling, also comprises a connecting body 215, for example one for each pumping chamber, which fluidically connects the suction channel and the delivery channel of a pumping chamber with respective sections of the delivery duct and of the suction duct of the corresponding pumping chamber which are made in the monolithic body 190. In particular, each connecting body comprises a first connecting channel 220 and a second connecting channel 225, which respectively place in fluid communication the suction channel of a pumping chamber with the section of the suction duct of said pumping chamber and the delivery channel with the section of the delivery duct of the respective pumping chamber.

Said first connecting channel 220 and second connecting channel 225 therefore constitute a section of the suction duct and of the delivery duct which is directly contiguous respectively to the suction channel 160 and to the delivery channel 165 of the respective pumping chamber.

Altogether, therefore, the section of the suction duct made in the monolithic body 190, and the section of the suction duct 160 constituted by the first connecting channel 220 together constitute the entire suction duct of each pumping chamber. Similarly, the section of the delivery duct made in the monolithic body 190, and the section of delivery duct constituted by the second connecting channel 225 together constitute the entire delivery duct of each pumping chamber.

It is not excluded that in an alternative embodiment the suction and delivery channels may not be present, in this case the first connecting channel 220 and the second connecting channel 225 extend directly starting from the suction and delivery mouths of the corresponding pumping chambers.

In the embodiment illustrated, the connecting body 215, i.e. each connecting body 215, is made as a distinct body from the central monolithic body 190, for example monolithic, and is fixed to the baseplate of the pump in a removable manner, for example by means of threaded connection members. The connecting body 215, i.e. each connecting body 215, is preferably made of a polymeric material.

By fixing said connecting body 215, i.e. the connecting bodies, to the baseplate, the caps 170 are clamped between the connecting body 215, i.e. the respective connecting body 215, and the baseplate 15. For example, this allows an annular sealing gasket 230 placed at a distal end from the pumping chamber of each delivery 165 and suction channel to be compressed, thereby creating a hermetic seal with the respective first and second connecting channel 225.

Each section of the suction or delivery duct made in the monolithic body 190 makes a respective opening (on one side of the section opposite the intersection volume) in a portion of external surface of the monolithic body 190, for example at a peripheral portion of the monolithic body 190, in particular at the perimeter edge of the monolithic body 190. The pairs of delivery and suction sections are made in different portions of the external surface, preferably angularly equidistant with respect to the axis of rotation X.

Each of these openings directly faces onto a homologous opening made by the respective connecting channel in a portion of external surface of the connecting body in direct contact with said surface portion of the monolithic body 190.

Each portion of external surface of the monolithic body 190 in which the pair of openings is made is complementary to the portion of external surface of the respective connecting body 215 in which the corresponding openings of the same suction and delivery ducts are made. In the embodiments illustrated, these portions of surfaces are flat and parallel to each other.

The suction 140 and the delivery 145 valves are positioned in respective housing seats which are at least partially made of at least one between the monolithic body 190 or the connecting body 215, that is the respective connecting bodies. Preferably each seat is made partly in the monolithic body 190 and partly in the adjacent connecting body, and at the opening made by the sections of ducts in the monolithic body 190 and at the opening made in the connecting bodies by the connecting channels, that is at a junction area between connecting bodies and monolithic body 190. In this way, the maintenance of the valves is quick and easy and there is no need to make special holes to insert the valves, as the valve housing is made up of the suction and delivery ducts, which being made in two divided bodies, can be substantially open to access the valves.

The housing seats substantially appear as enlarged portions (of enlarged diameter) of the respective delivery or suction duct, this enlarged portion being at said openings (coaxially to them).

Said first and second connecting channel 225 are shaped in such a way as to bend the flow of the fluid by substantially 90° in the passage from the channel to the respective duct. In particular, a first section of these connecting channels, directly contiguous to the suction channel 160 or to the delivery channel 165, is parallel to the axis of rotation X and a second section, contiguous to the first one, is perpendicular to the axis of rotation X. Each connecting body is made as a monolithic body, distinct from the central monolithic body 190. In this way, the production of the connecting channels by moulding is simplified. However, it is not excluded that in a less preferred embodiment they could be a single monolithic body 190, although this complicates the manufacture thereof.

In the embodiment of the pump 1 a illustrated in Figures 1 -9, there are three pumping chambers, of which a first pumping chamber 20, a second pumping chamber 20 and a third pumping chamber 20, which are arranged around the axis of rotation X angularly spaced from each other and substantially all intersected by a same plane perpendicular to the axis of rotation X. For example, said three pumping chambers are equidistant from each other, in particular so that the centres of the pumping chambers are 120° apart from each other along an imaginary circumference having its centre on the axis of rotation X and lying on a plane perpendicular to the axis of rotation X.

The first pumping chamber is in fluid connection with a first suction duct and a first delivery duct, the second pumping chamber is in fluid connection with a second suction duct and a second delivery duct, and the third pumping chamber is in fluid connection with a third suction duct and a third delivery duct.

As there are three pumping chambers, there are preferably three connecting bodies, of which a first connecting body 215, a second connecting body 215 and a third connecting body 215.

Each of these delivery and suction ducts has a section made in the monolithic body 190 and a section made in a respective connecting body. In particular, the first suction duct and the first delivery duct comprise a section (in the form of respective first connecting channel 220 and second connecting channel 225), made in the first connecting body, the second suction duct and the second delivery duct comprise a section (in the form of respective first connecting channel 220 and second connecting channel 225), made in the second connecting body, and the third suction duct and the third delivery duct comprise a section (in the form of respective first connecting channel 220 and second connecting channel 225) made in the third connecting body.

All the delivery and suction ducts comprise a respective section made in the monolithic body 190.

With particular reference to Figures 7-9, the first suction duct and the first delivery duct comprise a section, respectively 240 and 245, made in the monolithic body 190, the second suction duct and the second delivery duct comprise a section, respectively 250 and 255, made in the monolithic body 190, and the third suction duct and the third delivery duct comprise a section, respectively 260 and 265, made in the monolithic body 190.

A portion of the section 265 of the third delivery duct made in the monolithic body 190 is aligned with a portion of the section 240 of the first suction duct made in the monolithic body 190 along a direction parallel to the axis of rotation X.

In particular, said portion of the section 265 of the third delivery duct made in the monolithic body 190 is superimposed on said portion of the section 240 of the first suction duct made in the monolithic body 190 along the direction parallel to the axis of rotation X. In detail, in said alignment portion of the monolithic body 190, said portions of the sections are fluidically separated by a single same wall 205 (with non-zero thickness) transversal to the axis of rotation X.

The sections 245,250,255,260 made in the central monolithic body 190 of the remaining ducts are substantially coplanar with each other and have longitudinal axes lying on a plane perpendicular to the axis of rotation X.

The first suction duct, the second suction duct and the third suction duct, for example the respective sections 240,250,260 made in the monolithic body 190, intersect each other, in particular they intersect in the intersection volume 270, from which the inlet duct 195 develops. The first delivery duct, the second delivery duct and the third delivery duct, for example the respective sections 245,255,265 made in the monolithic body 190, intersect each other, in particular in the intersection volume 275, from which the outlet duct 200 develops.

The intersection volume of the delivery channels is eccentric with respect to the intersection volume of the suction channels with respect to the axis of rotation X.

Figure 10 schematically depicts an embodiment of the pump indicated with 1 b, which is based on the same inventive concept as the embodiment 1 a of Figures 1 -9, with sections of the delivery and suction ducts made in the same monolithic body 190. The pump 1 b, unlike 1 a, has five pumping chambers, of which a first pumping chamber 20, a second pumping chamber 20, a third pumping chamber 20, a fourth pumping chamber 20 and a fifth pumping chamber 20. The five pumping chambers are arranged about the axis of rotation X angularly spaced from each other and substantially all intersected by the same plane perpendicular to the axis of rotation X. For example, said five pumping chambers are equidistant from each other, in particular so that the centres of the pumping chambers are 72° apart along an imaginary circumference having its centre on the axis of rotation X and lying on a plane perpendicular to the axis of rotation X.

The first pumping chamber is in fluid connection with a first suction duct and a first delivery duct, the second pumping chamber is in fluid connection with a second suction duct and a second delivery duct, the third pumping chamber is in fluid connection with a third suction duct and a third delivery duct, the fourth pumping chamber is in fluid connection with a fourth suction duct and a fourth delivery duct, and the fifth pumping chamber is in fluid communication with a fifth suction duct and a fifth delivery duct.

As there are five pumping chambers, there are preferably five connecting bodies, of which a first connecting body 215, a second connecting body 215, a third connecting body 215, a fourth connecting body 215 and a fifth connecting body 215.

Each delivery and suction duct has a section made in the monolithic body 190 and a section made in a respective connecting body.

In particular, the first suction duct and the first delivery duct comprise a section (in the form of respective first connecting channel 220 and second connecting channel 225), made in the first connecting body, the second suction duct and the second delivery duct comprise a section (in the form of respective first connecting channel 220 and second connecting channel 225), made in the second connecting body, the third suction duct and the third delivery duct comprise a section (in the form of respective first connecting channel 220 and second connecting channel 225), made in the third connecting body, the fourth suction duct and the fourth delivery duct comprise a section (in the form of respective first connecting channel 220 and second connecting channel 225), made in the fourth connecting body, the fifth suction duct and the fifth delivery duct comprise a section (in the form of the respective first connecting channel 220 and second connecting channel 225), made in the fifth connecting body.

All the delivery and suction ducts comprise a respective section made in the monolithic body 190.

In particular, the first suction duct and the first delivery duct comprise a section, respectively 280 and 285, made in the monolithic body 190, the second suction duct and the second delivery duct comprise a section, respectively 290 and 295, made in the monolithic body 190, the third suction duct and the third delivery duct comprise a section, respectively 300 and 305, made in the monolithic body 190, the fourth suction duct and the fourth delivery duct comprise a section, respectively 310 and 315, made in the monolithic body 190, the fifth suction duct and the fifth delivery duct comprise a section, respectively 320 and 325, made in the monolithic body 190.

A portion of the section 295 of the second delivery duct made in the monolithic body 190 is aligned with a portion of the section 320 of the fifth suction duct made in the monolithic body 190 along a direction parallel to the axis of rotation X. In said alignment portion of the monolithic body 190, said portions of the sections are fluidically separated by a single same wall (with non-zero thickness) transversal to the axis of rotation X (said wall is not visible in the figures as it is a schematic representation).

Furthermore, a portion of the section 305 of the third delivery duct made in the monolithic body 190 is aligned with a portion of the section 310 of the fourth suction duct made in the monolithic body 190 along a direction parallel to the axis of rotation X. Also in said alignment portion of the monolithic body 190, said portions of the sections are fluidically separated by a single same wall (of non-zero thickness) transversal to the axis of rotation X (this wall is not visible in the figures as it is a schematic representation).

The sections in the central monolithic body 190 of the remaining ducts are essentially coplanar and have longitudinal axes lying on a plane perpendicular to the axis of rotation X.

In the embodiment of Figures 1 1 -15, the pumping chambers are arranged radially about the axis of rotation X, like in the previous embodiment, but in this embodiment for each pumping chamber the suction mouth and the delivery mouth, i.e. the suction channel 160 and the delivery channel 165, are at different distances from the axis of rotation X, for example with the suction mouth, i.e. the suction channel 160, being closer to the axis of rotation X than the delivery mouth, i.e. the delivery channel 165 (although the positions of the mouths, i.e. channels, could be reversed, provided that they are reversed for all the pumping chambers). Furthermore, the delivery channel 165 and the suction channel 160 of each pumping chamber are substantially aligned with respect to each other along a radial direction originating from the axis of rotation.

In this embodiment, the suction channelling comprises a single suction duct 330, e.g. annular, in direct fluid connection with all suction mouths 150, that is all suction channels 160, by means of a plurality of openings, one for each suction mouth 150, that is one for each suction channel 160. Said suction duct, in case it is annular (indifferently open or closed ring as illustrated in the figures), is substantially coaxial to the axis of rotation X, i.e. it at least partially surrounds the axis of rotation X. Furthermore, the suction duct 330 (understood as the liquid passage area) is (all) intersected by a plane perpendicular to the axis of rotation X.

An inlet duct 335 provided with an inlet mouth 336 adapted to be connected to a source of liquid to be pumped develop from the suction duct.

The delivery channelling also comprises a single delivery duct 340, for example annular, in direct fluid connection with all delivery mouths 155, that is with all delivery channels 165, by means of a plurality of openings, one for each delivery mouth 155, that is one for each delivery channel 165. This delivery duct, in case it is annular (indifferently open or closed ring as illustrated in the figures), is substantially coaxial to the axis of rotation X, i.e. it at least partially surrounds the axis of rotation X, and in the embodiment illustrated it is radially more external than the suction duct. Furthermore, the delivery duct 340 (understood as the liquid passage area) is (all) intersected by a plane perpendicular to the axis of rotation X, for example by the same plane perpendicular to the axis of rotation that also intersects the suction duct 330. An outlet duct 345 provided with an outlet mouth 350 adapted to be connected to a source of liquid to be pumped develops from the delivery duct 340.

The delivery valves 145 can be housed in the delivery channels or in a portion of the delivery duct. For example, they are partly housed in the respective delivery channel and partly in a respective portion of the delivery duct. The suction valves 140 can be housed in the suction channels or in a portion of the suction duct. For example, they are partly housed in the respective suction channel and partly in a respective portion of the suction duct.

Although the embodiment of the pump indicated with 1 d is the only one whose sliding axes of the pistons are inclined with respect to the axis of rotation of the swash plate, this peculiarity is applicable to the other embodiments of the pump, in particular the delivery and suction channellings of Figures 1 -10 can replace the delivery and suction channellings of the embodiment of Figure 15.

Figure 17 shows an embodiment of the pump indicated with 1 f which is substantially a variant of the pump 1 e of Figure 16. In pump 1 f, like in 1 e, the plate 45, i.e. the swash plates 45, rotate with respect to axes of rotation X’ and X” which are eccentric with respect to axis of rotation X of the drive shaft, but instead of a simple gear formed by the first and second toothed wheel, in pump 1 f the transmission of the motion from the drive shaft to the swash plate, i.e. to the swash plates, takes place by means of a planetary gearbox, for example entirely contained in the baseplate. This makes it possible to connect the pump to motors that run at high rotation speeds (above 1500 rpm), without the need to mount a gearbox on the output shaft of said motor.

In the embodiment illustrated, the planetary mechanism comprises a first toothed wheel 360 integral with the drive shaft 5’ in rotation about the axis of rotation X. For example, this first toothed wheel is made by removing material from the shaft, in order to contain the overall dimensions.

The planetary mechanism then comprises at least one satellite toothed wheel 365, preferably a plurality of satellite toothed wheels 365, which meshes (each) directly with the first toothed wheel 365 and which is rotatably associated with the baseplate 10 with respect to an axis of rotation which is eccentric to both the axis of rotation X and the axes of rotation X’ and X” of the swash plates.

Further, the planetary mechanism comprises a toothed wheel with internal toothing 370 which meshes directly with the satellite toothed wheel 365 i.e., with the plurality of satellite toothed wheels 365, and which rotates coaxially to the axis of rotation X.

A toothed wheel with external toothing 375 is rotationally integral with the toothed wheel with internal toothing 370 and which meshes with a second toothed wheel 380 (also with external toothing) rotationally integral with the swash plate, i.e. with the respective swash plate, with respect to the corresponding axis of rotation X’,X”.

The toothed wheel with internal toothing 370 is spaced from the toothed wheel with external toothing 375 along the axis of rotation X by a non-zero amount, in particular it is more distant from the swash plate along this axis of rotation. In addition, the wheel with external toothing 375 has a smaller pitch diameter with respect to a pitch diameter than the toothed wheel with internal toothing 370. The difference in diameter and the distance along the axis of rotation X make it possible to reduce the overall dimensions of the mechanism and to create a compact pump despite the planetary gearbox.

In all the embodiments illustrated, the pump, i.e. the baseplate, is in an oil bath, so there is an oil tank 355 fluidically connected to the internal volume of the baseplate.

The invention thus conceived is susceptible to several modifications and variations, all falling within the scope of the inventive concept.

Moreover, all the details can be replaced by other technically equivalent elements.

In practice, the materials used, as well as the contingent shapes and sizes, can be whatever according to the requirements without for this reason departing from the scope of protection of the following claims.